CN111189404A - Steel-concrete composite structure damage measurement system - Google Patents
Steel-concrete composite structure damage measurement system Download PDFInfo
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- CN111189404A CN111189404A CN202010027092.8A CN202010027092A CN111189404A CN 111189404 A CN111189404 A CN 111189404A CN 202010027092 A CN202010027092 A CN 202010027092A CN 111189404 A CN111189404 A CN 111189404A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/223—Supports, positioning or alignment in fixed situation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0232—Glass, ceramics, concrete or stone
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0234—Metals, e.g. steel
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/0289—Internal structure, e.g. defects, grain size, texture
Abstract
The invention discloses a steel-concrete combined structure damage measuring system, which comprises a fiber grating measuring group, a fiber grating temperature compensation group, a fiber grating demodulator, a display, an acoustic emission measuring device and an extensometer, wherein the fiber grating temperature compensation group is arranged on the fiber grating; the fiber bragg grating measurement group and the fiber bragg grating temperature compensation group are arranged on the surface of a steel beam at the interface of a longitudinal steel-concrete combined bridge, the surface of the steel beam at the interface of a transverse steel-concrete combined bridge and the surface of an embedded steel bar in a steel-concrete combined structure, the fiber bragg grating measurement group and the fiber bragg grating temperature compensation group are connected with a fiber bragg grating demodulator, the fiber bragg grating demodulator is connected with a display, and the acoustic emission measurement device comprises an acoustic emission sensor, a data line, a sensor fixing device and an acoustic emission collector; the acoustic emission sensor is arranged on the surface of the concrete plate and is connected with the acoustic emission collector through a data line, and the acoustic emission collector is connected with the display; the extensometer is pre-buried inside the concrete for measure the displacement difference between girder steel and the concrete.
Description
Technical Field
The invention belongs to the fields of fiber grating sensing detection, acoustic emission detection, displacement measurement and the like, and particularly relates to a comprehensive damage measurement system for a steel-concrete combined structure under the stress condition.
Background
The steel-concrete combined structure can give full play to the mechanical properties and advantages of steel and concrete, and is widely applied to bridge structures. The steel-concrete composite structure is generally provided with a large number of shear connectors between a steel structure and a concrete structure so as to ensure that the structure formed by two different materials can bear force and work cooperatively, but in actual engineering, due to the difference of the material performances of the two materials, slippage, cracking and the like are often generated at an interface. The mechanical properties of a steel structure and a concrete structure at the interface of the composite structure are the key of the performance of the steel-concrete composite structure, so how to accurately measure the performance at the interface of the steel-concrete composite structure becomes an important aspect for evaluating the working performance of the composite structure. However, the current technology cannot accurately measure the stress performance of the steel-concrete composite structure interface due to the characteristics of complex spatial structure, narrow operation space, two different performance materials and the like at the steel-concrete composite structure interface.
The fiber grating measurement technology is suitable for manufacturing high-precision and high-sensitivity measurement elements due to the advantages of small measurement element size, good wavelength selectivity, no influence of nonlinear effect, strong anti-jamming capability, small additional loss and the like, and the resonance wavelength of the fiber grating measurement technology is sensitive to the change of external environments such as temperature, strain and the like, so that the fiber grating measurement technology is widely applied to the engineering strain measurement fields such as highways, bridges, dams, mines, airports, ships, railways, pipelines and the like. The existing fiber grating technology can accurately and rapidly measure strain and temperature change by engraving a grating on an optical fiber. The strain monitoring of the steel beam at the interface of the steel-concrete combined structure has important significance for determining the working states of steel and concrete in the combined structure, and is the key for evaluating the health state of the combined structure and predicting potential safety hazards in advance. A large number of shear connectors are usually arranged at the interface of the steel-concrete combined structure, the structure is complex, and the operation space is narrow. Concrete is required to be poured after the measuring element is installed, and the reliability and the stability of the measuring element are higher. The existing measuring method mainly comprises a resistance type strain measuring method and a steel string type strain measuring method, wherein the resistance type strain measuring method is extremely easy to be interfered in an electromagnetic environment and cannot accurately measure strain in a modern railway electrification environment; the steel string measuring element has larger volume, can only obtain the average strain within a certain gauge length range, and has larger installation difficulty within a narrow range. Secondly, the steel string looseness of the steel string type strain gauge can occur in the long-term service process, so that the accuracy is reduced. In conclusion, the fiber bragg grating strain sensing-based steel beam strain measurement method at the steel-concrete composite bridge interface can exert the advantages of small optical fiber volume and good anti-interference performance, overcomes the defects that the traditional resistance sensor is easily subjected to electromagnetic interference and the steel string of the steel string sensor is loose, and can more accurately measure the steel beam strain in the steel-concrete composite structure.
The application of acoustic emission technology at home and abroad has been for decades, and has been widely noticed by engineers and researchers, and the acoustic emission technology is initially applied to the measurement of the crack performance of homogeneous materials such as steel and the like, and then gradually expands to the measurement of the crack performance of heterogeneous materials such as rocks and the like. However, further analysis and research are still needed in terms of acoustic emission mechanism, signal characteristics, theoretical analysis, test standards, and the like. The concrete material has low tensile strength due to the structural characteristics of the concrete material, and internal and surface cracks are easy to generate in the stress process. The existing crack measuring equipment can only measure the width and the depth of a crack on the surface of concrete, and cannot measure the crack information inside the concrete. A composite bridge comprises a steel beam, a concrete slab, and a shear connection therebetween. The formation of the internal cracks of the concrete is influenced by external load and simultaneously is restrained by internal reinforcing steel bars, the internal stress of the concrete of the steel-concrete composite bridge is complex, and the cracking and damaging processes of the concrete are also complex. The acoustic emission technology is used for measuring and analyzing the generation position and the crack performance of the internal crack of the concrete by receiving an acoustic signal generated in the cracking process of the internal crack of the concrete, so that the crack generation process and the crack mechanism are researched, and the acoustic emission technology belongs to a dynamic measurement process.
The accurate measurement of the slippage between a steel beam and a concrete slab of a steel-concrete composite bridge is the key of a test technology of the composite bridge, and the current measurement technology can only measure the relative displacement between the steel and the concrete at the outer surface of a steel-concrete structure, but cannot accurately measure the relative slippage between the internal concrete and the steel beam.
The invention provides four measuring methods for determining the performance of a steel-concrete combined structure interface, ① provides a fiber grating measuring method for measuring the strain of a steel structure at the interface, ② provides an acoustic emission measuring method for measuring the performance of concrete at the interface, ③ provides a relative displacement measuring method for measuring the slippage of the concrete and a steel beam in the combined structure interface, and ④ provides a fiber grating measuring method for measuring the strain of a steel bar of the combined structure.
The stress performance of the steel-concrete combined structure under the stress condition is comprehensively monitored based on the four measurement methods provided by the invention, the monitoring results of the methods are integrated, the comprehensive system calculation is carried out, and the damage of the steel-concrete combined structure is judged.
Disclosure of Invention
The invention aims to provide a ① steel beam strain measuring device at an interface of a steel-concrete combined structure based on fiber bragg grating strain sensing, which solves the problems in the prior art, the prior strain measuring technology has the defects of poor electromagnetic interference resistance, large measuring element volume, poor measuring stability and the like, and is not suitable for the strain measurement of a steel beam of a railway steel-concrete combined bridge.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
a steel-concrete composite structural damage measurement system, comprising: the fiber grating measurement group 31, the fiber grating temperature compensation group 33, the fiber grating demodulator, the display, the acoustic emission measurement device and the extensometer 102;
the fiber bragg grating measurement group 31 and the fiber bragg grating temperature compensation group 33 are arranged on the surface of the steel beam 74 at the longitudinal steel-concrete composite bridge interface, the surface of the steel beam 74 at the transverse steel-concrete composite bridge interface and the surface of the embedded steel bar 111 in the steel-concrete composite structure,
the fiber bragg grating measurement group 31 is used for measuring the strain of the steel beam 74 at the longitudinal steel-concrete composite bridge interface, the strain of the steel beam 74 at the transverse steel-concrete composite bridge interface and the strain of the embedded steel bar 111 in the steel-concrete composite structure,
the fiber grating temperature compensation group 33 is used for measuring wavelength change caused by temperature change and eliminating the influence of the temperature change on measurement data;
the fiber grating measurement group 31 and the fiber grating temperature compensation group 33 are connected with a fiber grating demodulator through the optical fiber 12, and send measurement data to the fiber grating demodulator;
the fiber grating demodulator is connected with the display and used for receiving and processing the measurement data and sending the processed data to the display;
the acoustic emission measurement device includes: acoustic emission sensor 61, data line 75, sensor fixing device and acoustic emission collector;
the acoustic emission sensor 61 is mounted on the surface of the concrete slab 73 by a sensor fixing means,
the acoustic emission sensor 61 is connected with the acoustic emission collector through a data line 75, and is used for sending the collected acoustic signals to the acoustic emission collector,
the acoustic emission collector is connected with the display and used for receiving the acoustic signals, analyzing and calculating the acoustic signals, and sending the processing result to the display for displaying after the analysis processing is finished;
the extensometer 102 is pre-buried inside concrete 103, one end of the extensometer 102 is connected to the surface of the steel beam through welding, the other end of the extensometer is connected with the polished and bright steel beam, silicone rubber is coated 704 at the joint for soft protection, one end of the extensometer is used for representing the displacement deformation of the steel beam, the other end of the extensometer is used for representing the displacement deformation of the concrete, and the extensometer 102 is used for measuring the displacement difference between the steel beam and the concrete and transmitting the measurement result to the display.
On the basis of the scheme, before the fiber grating measurement group 31 and the fiber grating temperature compensation group 33 are installed, the fiber grating 11 is pre-stressed, and the fiber grating 11 is placed in the optimal measurement range.
On the basis of the above scheme, the installation process of the fiber grating measurement group 31 and the fiber grating temperature compensation group 33 is specifically as follows:
polishing the measurement position to ensure that the fiber bragg grating measurement group 31 and the fiber bragg grating temperature compensation group 33 are in effective contact with the measured object;
the outer layers of the N fiber gratings 11 in the fiber grating temperature compensation group 33 are provided with plastic sleeves to form a plastic sleeve isolation layer 37, then 704 silicone rubber and epoxy resin glue are sequentially coated to form 704 silicone rubber isolation layer 36 and epoxy resin glue protection layer 32, and the plastic sleeves are used for isolation, so that the fiber gratings 11 are not deformed together with the measured object;
the 704 silicone rubber isolation 36 layer is used for soft protection, so that the interaction between the fiber grating 11 at the measuring point and the concrete 103 is reduced, the common deformation of the fiber grating 11 and the measured object is ensured, and the measurement precision is improved;
the epoxy resin glue protective layer 32 is used for hard protection, and ensures that the fiber grating 11 is not damaged in the concrete 103 pouring process.
On the basis of the scheme, the measurement gauge length of the fiber grating 11 is 1-10 mm.
On the basis of the scheme, the acoustic emission sensor 61 adopts a broadband sensor with an acoustic emission bandwidth of 100kHz-1.0 MHz.
On the basis of the above scheme, the sensor fixing device includes: steel fixed frame 93, steel column 91, fixed spring 92 and two iron sheets 95, be equipped with the through-hole on steel fixed frame 93, steel column 91 passes fixed spring 92 in proper order, the through-hole, the setting is on steel fixed frame 93, the lower extreme of steel column 91 is equipped with the disc, install the concrete surface after polishing behind acoustic emission sensor 61 surface coating couplant 96, iron sheet 95 pastes on concrete 103 surface through powerful glue, steel fixed frame 93's bottom is made by magnet 94, adsorb on iron sheet 95, the top of acoustic emission sensor 61 is arranged in to the disc that makes steel column 91 lower extreme, then make acoustic emission sensor 61 closely laminate with the concrete surface through pressing steel column 91.
On the basis of the scheme, the measuring gauge length of the extensometer 102 is 1-10 cm.
Has the advantages that:
① the invention uses the fiber grating measuring method for the steel beam strain measurement at the steel-concrete composite bridge interface, the grating is pasted and fixed on the top of the steel beam at the tested composite bridge interface, the measuring scale distance of the grating is 1-10mm, the grating space can be changed after the steel beam is deformed, thereby changing the reflected light wavelength of the grating, the fiber grating demodulator processes, it can accurately measure the steel beam strain at the steel-concrete composite bridge interface.
The measured surface is polished smooth before the optical fiber is pasted, the optical fiber grating is adjusted to the optimal measurement range by applying a prestress mode before the optical fiber is pasted, the optical fiber grating can be tightly bonded with the steel surface, and after the pasting is finished, the installation is carried out by the soft protection scheme and the hard protection scheme in the invention, so that the accuracy and the effectiveness of the measurement method are ensured, and the reliability of the measurement method is improved.
② A method for measuring internal cracks of concrete of a steel-concrete composite bridge by using acoustic emission technology.
The steel-concrete composite bridge includes: the steel beam, the concrete slab and the shear connecting piece between the steel beam and the concrete slab;
the measuring apparatus includes: the device comprises a broadband sensor with an acoustic emission bandwidth of 100kHz-1.0MHz, an acoustic emission collector, a sensor fixing device and a display; the acoustic emission sensor is arranged on the surface of the concrete slab through a fixing device and is connected with the acoustic emission collector through a data line.
In the stress process of the steel-concrete composite structure, cracks are generated in the concrete slab, the cracks are quickly released along with the elastic wave in the development process, acoustic signals are collected by acoustic emission sensors arranged on the surface after being transmitted to the surface of the concrete in the concrete, the acoustic signals are transmitted to an acoustic emission collector through a data connecting line, the acoustic emission collector analyzes and calculates the acoustic signals, the positions of the cracks generated in the concrete slab are determined through a mathematical algorithm according to the time difference of the signals received by the sensors, and the crack performance is analyzed through the characteristics of the acoustic signals. On the basis of determining the crack position and the performance, the characteristics of the internal cracks of the concrete of the steel-concrete composite bridge are analyzed, so that the stress performance of the concrete slab of the steel-concrete composite bridge under the combined action of the steel bars and the shear connectors is analyzed. Before testing, the crack positioning function of the method is calibrated through the concrete bending-resistant beam.
The acoustic emission technology applied to the measurement of the internal cracks of the concrete of the steel-concrete composite bridge can fill the blank that the internal cracks of the concrete cannot be measured in the prior art, dynamically acquires crack information in the stress process of a steel-concrete composite structure, can dynamically monitor the generation and development processes of the internal cracks of the concrete, forms a three-dimensional distribution map of the cracks in a three-dimensional space, and is used for acquiring and analyzing the internal crack information of the concrete.
③ the invention adopts the method of embedded high precision extensometer to measure the relative slippage between the steel beam and the concrete at the interface.
④ the invention provides a method for measuring the strain of steel bar in steel-concrete composite structure by fiber grating measurement method, which can continuously and accurately measure the strain of steel bar in the stress process of steel-concrete composite structure by sticking continuous grating measurement points on the surface of steel bar.
Drawings
FIG. 1 is a schematic view of a device for measuring the strain of a steel beam at an interface of a railway steel-concrete composite bridge according to the present invention;
FIG. 2 is a cross section of a steel-concrete composite bridge, wherein a fiber grating arrangement area is arranged in a circle area;
FIG. 3 is a detail view of fiber grating mounting details;
FIG. 4 is a view of a transverse fiber grating arrangement;
FIG. 5 is a view of the arrangement of the transverse and longitudinal fiber gratings;
FIG. 6 is a schematic view of an acoustic emission measurement system calibration of the present invention;
FIG. 7 is an overall connection diagram of the acoustic emission measurement system of the present invention;
FIG. 8 is a schematic plan view of the acoustic emission measurement principle of the present invention;
FIG. 9 is a schematic view of the stationary mounting of the acoustic emission sensor of the present invention;
FIG. 10 is a drawing of a steel and concrete slip device at a measuring interface of the present invention using an in-line extensometer method;
FIG. 11 is a diagram of a device for measuring the strain of the steel bar by using fiber gratings according to the present invention.
FIG. 12 is a system for measuring damage to a steel-concrete composite structure according to the present invention by integrating the measurement results of the respective methods.
In the figure: 11-fiber grating; 12-an optical fiber; 31-fiber grating measurement group; 32-epoxy resin glue protective layer; 33-fiber grating temperature compensation group; 35-quick-drying type super glue; 36-704 silicone rubber barrier layer; 37-plastic sleeve isolation layer; 41-transverse fiber grating; 51-longitudinal steel bars; 52-transverse reinforcement; 53-longitudinal fiber grating; 61-an acoustic emission sensor; 73-a concrete slab; 74-steel beam; 75 — data lines; 91-steel column; 92-a fixed spring; 93-steel fixed frame; 94-a magnet; 95-iron sheet; 96-a coupling agent; 102 — extensometer; 103-concrete; 111-steel reinforcement; 112-steel bar polishing surface; 113-grating region.
Detailed Description
The technical scheme is completely described in detail by combining the attached drawings 1-12.
The invention provides a fiber grating sensing and measuring device which can be applied to monitoring the strain of a steel beam at a railway steel-concrete bridge interface, can accurately measure the strain of the steel beam at the railway steel-concrete composite bridge interface, effectively evaluate the health state of a bridge, prevent potential safety hazards in advance and avoid major safety accidents.
Fig. 1 shows a schematic diagram of a fiber grating measuring device, in which a fiber grating measuring element is adhered to the surface of a steel beam at the interface of a steel-concrete composite bridge, and is connected with a fiber grating demodulator through an optical fiber, and the demodulator processes the wavelength of emitted light and transmits the processed information to a calculation information acquisition system for analysis.
FIG. 2 shows the installation position of the fiber grating at the interface of the steel-concrete composite bridge.
FIG. 3 is a detailed diagram of an implementation of the fiber grating installation method, which is described in detail in the following steps of grinding a ① junction surface steel beam measurement position to ensure that a measurement element is in effective contact with a measured object, installing ② a fiber grating measurement group 31 and a fiber grating temperature compensation group 33 at the measurement position, wherein a fiber grating 11 in the fiber grating measurement group 31 is adhered to the surface of the steel beam through quick-drying type strong glue, installing a plastic sleeve on the outer layer of the fiber grating 11 in the fiber grating temperature compensation group 33 to isolate the fiber grating 11 from the measured object without deforming together with the measured object, and only measuring wavelength changes caused by temperature changes, applying prestress to the optical fiber according to the stress characteristics of the structure measurement position, placing the optical fiber in an optimal measurement range, coating ③ silicone rubber on the adhered surface of the optical fiber to form a silicone rubber isolation layer 36, performing soft protection, reducing interaction between the grating and concrete at the measurement point, ensuring that the fiber grating measurement element and the measured steel beam deform together, and improving the measurement accuracy, coating ④ epoxy resin outside the silicone rubber isolation layer 704 to perform hard protection, and ensuring that the optical fiber is not damaged in.
Through specific installation and measurement system installation, the steel beam strain at the interface of the steel-concrete composite bridge can be accurately measured through the fiber grating device, and the influence of temperature change is eliminated through the fiber grating measurement data of the temperature compensation group.
The fiber grating measuring method can arrange measuring elements at the joint surfaces of the longitudinal bridge direction and the transverse bridge direction, such as a transverse fiber grating 41 shown in fig. 4, a longitudinal fiber grating 52 shown in fig. 5 on a longitudinal steel bar 51, and a longitudinal fiber grating 53 on a transverse steel bar 52, so as to measure the steel structure strain of the steel-concrete composite bridge in the longitudinal bridge direction and the transverse bridge direction.
As shown in FIG. 6, the acoustic emission measurement device of the present invention calibrates the crack positioning function through the bending process of the concrete bending-resistant test piece. The method comprises the steps of installing an acoustic emission measuring device on the surface of a concrete bending-resistant test piece, collecting an acoustic emission signal in the crack generation process in the bending process of the test piece, and calibrating the crack positioning function of the acoustic emission measuring device by comparing the position of the crack on the surface of the test piece with the position of the crack generated by the acoustic emission signal.
As shown in fig. 7, the acoustic emission measurement device of the present invention includes: acoustic emission sensor 61, data line 75, acoustic emission collection appearance and sensor fixing device. The acoustic emission sensor is fixed on the surface of a concrete slab 73 of a steel-concrete combined structure, collects crack information inside the concrete, transmits the crack information to the acoustic emission collector through a connecting wire, and displays the generation position and characteristics of cracks inside the concrete after processing and analysis, so that the aim of collecting and analyzing the performance of the cracks inside the concrete is achieved.
As shown in fig. 8, the acoustic emission measurement device of the present invention works on the principle that when a crack is generated in the concrete, the acoustic wave is rapidly released in the form of an elastic wave, and the acoustic wave propagates in the concrete and reaches the surface of the concrete, and is transmitted to the acoustic emission collector through the connecting line after being received by the acoustic emission sensor fixed on the surface of the concrete, so as to complete the collection of the crack generation position and the crack performance. According to the propagation speed of elastic waves in the reinforced concrete material and the time difference of acoustic signals received by each sensor, the position of a sound source is determined by means of a space positioning algorithm, the characteristics of the acoustic signals are obtained through integration and a statistical algorithm of the acoustic signals, the frequency domain characteristics of the acoustic signals are obtained through Fourier transform, and the frequency domain related characteristics of the acoustic signals can be analyzed. After the acquisition and treatment analysis are completed, the performance of the internal cracks of the concrete of the steel-concrete composite bridge can be summarized.
FIG. 9 provides a detailed illustration of the installation of an acoustic emission sensor on a concrete surface. The acoustic emission sensor is mounted on the surface of the concrete slab 73 by a sensor fixing device. The sensor fixing device includes: steel fixed frame 93, steel column 91, fixed spring 92 and two iron sheets 95, be equipped with the through-hole on steel fixed frame 93, steel column 91 passes fixed spring 92 in proper order, the through-hole, the setting is on steel fixed frame 93, the lower extreme of steel column 91 is equipped with the disc, install the concrete surface after polishing behind acoustic emission sensor 61 surface coating couplant 96, iron sheet 95 pastes on concrete 103 surface through powerful glue, steel fixed frame 93's bottom is made by magnet 94, adsorb on iron sheet 95, the top of acoustic emission sensor 61 is arranged in to the disc that makes steel column 91 lower extreme, then make acoustic emission sensor 61 closely laminate with the concrete surface through pressing steel column 91. After the acoustic emission sensor 61 is installed, an effective measurement range is determined according to the model and the performance of the acoustic emission sensor after acoustic testing, a monitoring range is determined according to the stress characteristics of the composite structure and the range formed by cracks, and finally, the arrangement form is determined based on the effective measurement range of the acoustic emission sensor and the area to be measured, and only one arrangement mode is given in fig. 7.
In the method shown in fig. 10, a high-precision extensometer is pre-embedded in the concrete, and the measurement gauge length of the extensometer 102 is 1-10 cm. One end of the extensometer is connected to the surface of the steel beam through a welding method, the steel beam at the other end is polished to be bright and then glue 704 is smeared between the steel beam and the extensometer for soft protection, and the mortar is placed to be hardened to generate adhesive force. The extensometer welded one end represents the displacement deformation of the steel beam and the other end represents the displacement deformation of the concrete, thereby measuring the displacement difference between the two. According to the method, the extensometer is embedded in the concrete, the measuring process and the measuring method are high in external interference resistance and reliability, and the relative displacement of the steel beam and the concrete can be accurately measured.
The method shown in fig. 11 is to apply the fiber grating measurement method to the measurement of the strain of the embedded steel bar in the steel-concrete composite structure. Firstly, polishing the surface of a measured steel bar to form a steel bar polishing surface 112, cleaning the steel bar polishing surface with alcohol, applying prestress to the optical fiber according to the first part of the fiber bragg grating measurement and installation method, then pasting the optical fiber, and then performing soft protection and hard protection.
Fig. 12 shows that the measurement method proposed by the present invention is applied to a steel-concrete composite structure, the measurement result is subjected to comprehensive system calculation, and the damage of the steel-concrete composite structure is evaluated after the result is synthesized, so as to form a damage measurement system of the steel-concrete composite structure.
Those not described in detail in this specification are within the skill of the art.
Claims (7)
1. A steel-concrete composite structure damage measurement system, comprising: the device comprises a fiber grating measuring group (31), a fiber grating temperature compensation group (33), a fiber grating demodulator, a display, an acoustic emission measuring device and an extensometer (102);
the fiber bragg grating measurement group (31) and the fiber bragg grating temperature compensation group (33) are arranged on the surface of a steel beam (74) at the longitudinal steel-concrete combined bridge interface, the surface of the steel beam (74) at the transverse steel-concrete combined bridge interface and the surface of an embedded steel bar (111) in a steel-concrete combined structure,
the fiber bragg grating measurement group (31) is used for measuring the strain of a steel beam (74) at the interface of a longitudinal steel-concrete combined bridge, the strain of the steel beam (74) at the interface of a transverse steel-concrete combined bridge and the strain of an embedded steel bar (111) in a steel-concrete combined structure,
the fiber bragg grating temperature compensation group (33) is used for measuring wavelength change caused by temperature change and eliminating the influence of the temperature change on measurement data;
the fiber grating measurement group (31) and the fiber grating temperature compensation group (33) are connected with a fiber grating demodulator through an optical fiber (12), and the measurement data is sent to the fiber grating demodulator;
the fiber grating demodulator is connected with the display and used for receiving and processing the measurement data and sending the processed data to the display;
the acoustic emission measurement device includes: the acoustic emission sensor (61), the data line (75), the sensor fixing device and the acoustic emission collector;
the acoustic emission sensor (61) is mounted on the surface of a concrete slab (73) through a sensor fixing device,
the acoustic emission sensor (61) is connected with the acoustic emission collector through a data line (75) and is used for sending collected acoustic signals to the acoustic emission collector,
the acoustic emission collector is connected with the display and used for receiving the acoustic signals, analyzing and calculating the acoustic signals, and sending the processing result to the display for displaying after the analysis processing is finished;
the extensometer (102) is pre-buried inside concrete (103), one end of the extensometer (102) is connected to the surface of a steel beam through welding, the other end of the extensometer is connected with the polished and bright steel beam, 704 silicon rubber is coated at the joint for soft protection, one end of the extensometer is used for representing displacement deformation of the steel beam, the other end of the extensometer is used for representing displacement deformation of the concrete, and the extensometer (102) is used for measuring displacement difference between the steel beam and the concrete and transmitting a measuring result to a display.
2. A steel-concrete composite structure damage measurement system according to claim 1, characterized in that the fiber grating (11) is pre-stressed before the fiber grating measurement set (31) and the fiber grating temperature compensation set (33) are installed, placing the fiber grating (11) in the optimal measurement range.
3. The steel-concrete composite structure damage measurement system of claim 2, wherein the fiber grating measurement group (31) and the fiber grating temperature compensation group (33) are installed in the following specific steps:
polishing the measurement position to ensure that the fiber bragg grating measurement group (31) and the fiber bragg grating temperature compensation group (33) are in effective contact with the measured object;
n fiber gratings (11) in the fiber grating measuring group (31) are adhered to the surface of a steel beam through quick-drying type strong glue (35), and then 704 silicon rubber and epoxy resin glue are sequentially coated on the surface of the fiber gratings (11) to form 704 silicon rubber isolation layers (36) and epoxy resin glue protection layers (32);
the outer layers of N fiber gratings (11) in the fiber grating temperature compensation group (33) are provided with plastic sleeves to form a plastic sleeve isolation layer (37), then 704 silicone rubber and epoxy resin glue are sequentially coated to form a 704 silicone rubber isolation layer (36) and an epoxy resin glue protection layer (32), and the plastic sleeves are used for isolation, so that the fiber gratings (11) are not deformed together with a measured object;
the 704 silicone rubber isolation layer (36) is used for soft protection, reduces the interaction between the fiber grating (11) and the concrete (103) at the measuring point, ensures that the fiber grating (11) and the measured object deform together, and improves the measurement precision;
the epoxy resin glue protective layer (32) is used for hard protection, and the fiber bragg grating (11) is guaranteed not to be damaged in the concrete (103) pouring process.
4. A steel-concrete composite structure damage measurement system according to claim 2, characterized in that the measurement gauge length of the fiber grating (11) is 1-10 mm.
5. The steel-concrete composite structure damage measurement system of claim 1, wherein the acoustic emission sensor (61) is a broadband sensor with an acoustic emission bandwidth of 100kHz to 1.0 MHz.
6. The steel-concrete composite structural damage measurement system of claim 1, wherein the sensor fixing means comprises: steel fixed frame (93), steel column (91), fixed spring (92) and two iron sheets (95), be equipped with the through-hole on steel fixed frame (93), steel column (91) pass fixed spring (92) in proper order, the through-hole, the setting is on steel fixed frame (93), the lower extreme of steel column (91) is equipped with the disc, install the concrete surface after polishing after acoustic emission sensor (61) surface coating couplant (96), iron sheet (95) are pasted on concrete (103) surface through powerful glue, the bottom of steel fixed frame (93) is made by magnet (94), adsorb on iron sheet (95), the top of acoustic emission sensor (61) is arranged in to the disc that makes steel column (91) lower extreme, then make acoustic emission sensor (61) closely laminate with the concrete surface through pressing steel column (91).
7. A steel-concrete composite structure damage measurement system according to claim 1, wherein the extensometer (102) measures a gauge length of 1-10 cm.
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